A common conduit fitting utilizes a male adapter having a conical nose which engages a flared or conical surface defined upon a conduit, or fitting component associated with the conduit, wherein the conical surfaces of the fitting parts engage in metal-to-metal relationship. A nut, or similar axial force producing device, is used to produce engagement of the conical fitting surfaces.
Unless the conical fitting surfaces are substantially concentric and accurately formed free of scratches and dents, leakage may result even though the nut is fully tightened. Also metal "creep" and cold flow over a duration of time may result in dimensional changes permitting leakage, and in the past, problems have been encountered in fluid systems using conical adapter coupling components permitting leakage, and where such fittings are not located as to be readily observable, the failure of the fitting can produce serious problems, and render the associated fluid conduit inoperable.
The dependability of fittings utilizing conical nose surfaces, such as of the 37.degree. or 45.degree. type, can be improved by utilizing a metal seal intermediate the axially aligned conical surfaces of the fitting parts. The engagement of the fitting conical surfaces with a metal seal permits the seal to deform, if necessary, to accommodate itself to machining inaccuracies and nonconcentric relationships, but such a metal seal is still subject to cold flow displacement over extended durations, and may leak if the nose is scratched or dented. In systems wherein long life dependability is important, metal seals have been utilized between the conical surfaces of fittings, particularly in refrigeration circuits, but cold flow problems have not achieved the absolute 100% dependability desired.
It is an object of the invention to provide a seal for use with conduit fittings employing axially aligned conical surfaces wherein the seal permits metal-to-metal engagement, and additionally, provides elastomeric sealing to maintain the integrity of the seal even in the presence of metal flow.
An additional object of the invention is to provide a seal for use with conical face fittings wherein the seal utilizes both metal-to-metal and elastomeric sealing characteristics, and the seal is economical to manufacture and readily installable.
In the practice of the invention, the seal used with the fitting is mounted upon the male adapter adjacent the conical nose surface thereof, and the seal is of an annular configuration formed of steel, aluminum, brass, etc. The seal body includes a cylindrical portion received upon a cylindrical adapter surface, and a cone depending therefrom which overlies a portion of the adapter conical surface.
The inner end of the seal cone has an elastomeric tip or ring bonded thereto, and the radial dimension of the cone is such that both the metal and elastomeric sections thereof will be located between the conical surfaces of both halves or portions of the assembled fitting. Thus, both the metal and elastomer portions of the seal will be under compression upon the fitting being fully assembled.
The metal conical portion of the seal permits metal-to-metal sealing, while the elastomeric portion provides the efficient sealing characteristics of an elastomer seal. The seal accommodates itself to surface irregularities present in the fitting conical surfaces, and dimensional changes that may occur due to metal flow will be accommodated by the self-expanding characteristics of the elastomer to maintain the integrity of the fitting over long durations.